This Core is responsible for all epidemiological, statistical, and data management aspects of the Program Project. The Division of Clinical Epidemiology, including the Rochester Epidemiology Project, provides the nucleus for the population-based Project 1 by assuming complete ascertainment of all clinical aspects pertaining to the residents of Olmsted County. This includes coordination of our access to the records of other patient core providers, determination of residency, and ongoing maintenance of county demographic, survival, and disease rate databases. The Division of Biostatistics provides statistical expertise including state of the art analysis and data management resources to all the investigators but especially for Projects 1, 3, 4, and 5, which assess factors across the patient population and/or analyze gene expression data using microarray technology. The Core will also provide support, albeit to a lesser extent, to specific aims within projects that are more laboratory based and hypothesis-seeking in nature. The Survey Research Center, within the Division of Biostatistics, provides expertise in the contact and follow-up of Mayo patients and will be particularly important to Project 1. The existence of this Core assures a uniform plan of protocol design, data handling, and statistical analysis, facilitates the sharing of data and samples among the projects, and assures that appropriate resources are available to all investigators.